The long-term objectives of the proposed research are (a) to understand the characteristics of individuals, the conditions, and the processes that influence the occurrence of drug-taking, drug dependence, and other forms of serious drug involvement amongst Latin American youths, particularly drug involvement that occurs in clusters; and (b) to translate this understanding into practical public health strategies for the prevention and control of hazards associated with drug-taking in this important and growing segment of the world's population. The project involves a centrally coordinated multi-site cross-sectional survey of teenage drug involvement in the seven countries of Latin America that now participate in the Inter- American Drug Abuse Control Commission (CICAD): Dominican Republic, Panama, El Salvador, Costa Rica, Guatemala, Honduras, and Nicaragua. This project builds from the infrastructure of past CICAD efforts that were intended to quantify the prevalence of youthful drug-taking in these countries. As planned, the project will include the use of standardized classroom survey methods to produce the first nationwide probability sample survey estimates of teenage drug-taking in this region of the America. The research also will use a newly developed statistical procedure ("alternating logistic regression") to examine the degree to which non-medical drug use and other forms of drug involvement might appear in clusters within the boundaries of classrooms, schools, and other local area aggregations of these countries. When the proposed research is completed, the result will be a substantially increased understanding of the epidemiology of adolescent alcohol and drug involvement in the Central American region, as well as a more substantial foundation for NIH-supported international collaborative research in the participating countries. The research plan includes deliberate attention to publication of scientific articles in peer-reviewed journals, which will help to strengthen the participating countries infrastructure for collaborative research beyond the duration of this grant award.